Carboxylate-based well bore treatment fluids

Abstract

This invention relates to novel compositions and methods whereby a carboxylate based brine solution is used in drilling and/or well bore treating operations to inhibit corrosion of fluid handling equipment. In one embodiment of the invention the carboxylate based brine solution consists of a carboxylate salt dissolved in water. This brine solution is used to prepare halide-free drilling fluids. Use of halide-free drilling fluids inhibits corrosion stainless steel surfaces of fluid handling equipment. In an alternative embodiment of the present invention a mixed salt brine containing a carboxylate salt and a halide salt is provided for use in a drilling and/or well bore treating operations.

What is claimed is:  
     
       1. A method of inhibiting corrosion on a metal well surface comprising: 
       combining a brine with an aqueous composition having a density of 8 ppg or more at 70° F. and comprising carboxylate salt, and  
       contacting the brine/carboxylate salt combination with the metal well surface.  
     
     
       2. The method of claim  1 , wherein the carboxylate salt is present at a concentration of about 1 weight % to about 84 weight % of the aqueous composition. 
     
     
       3. The method of claim  1 , wherein the carboxylate salt is a C1 to C5 carboxylate salt. 
     
     
       4. The method of claim  1  wherein the carboxylate salt is an alkali metal or alkaline earth metal carboxylate salt. 
     
     
       5. The method of claim  1  wherein the carboxylate salt is selected from the group consisting of sodium formate, sodium acetate, and sodium propionate. 
     
     
       6. The method of claim  1  wherein the aqueous composition is saturated with carboxylate salt. 
     
     
       7. The method of claim  1  wherein the aqueous composition is substantially free of solids. 
     
     
       8. The method of claim  1  wherein the aqueous composition is essentially halide free. 
     
     
       9. The method of claim  1  wherein the aqueous composition has a density of about 8 ppg to about 19 ppg at 70° F. and consists essentially of water and carboxylate salt. 
     
     
       10. The method of claim  8  wherein the aqueous composition consists essentially of water and an amount of the carboxylate salt sufficient to provide an aqueous composition having a density of about 8.4 ppg to about 9.8 ppg. 
     
     
       11. The method of claim  1  wherein the metal surface comprises stainless steel. 
     
     
       12. The method of claim  1  wherein the metal surface comprises carbon steel. 
     
     
       13. The method of claim  1  wherein the combination of the aqueous composition and the brine further comprises carbon dioxide or hydrogen sulfide or a combination thereof dissolved or entrained therein. 
     
     
       14. A method of inhibiting corrosion on a metal well surface comprising: 
       combining a brine with an aqueous composition having a density of 8 ppg or more at 70° F. and comprising carboxylate salt and halide salt, and contacting the brine/carboxylate salt combination with the metal well surface.  
     
     
       15. A method of conditioning a metal well surface in contact with an aqueous brine having dissolved or entrained therein carbon dioxide comprising: 
       combining the brine with an aqueous composition having a density of 8 ppg or more at 70° F. and comprising carboxylate salt, and contacting the brine/carboxylate salt combination with the metal well surface.  
     
     
       16. The method of claim  15 , wherein the carboxylate salt is present at a concentration of about 1 weight % to about 84 weight % of the aqueous composition. 
     
     
       17. The method of claim  15  wherein the carboxylate salt is a C1 to C5 carboxylate salt. 
     
     
       18. The method of claim  15  wherein the carboxylate salt is an alkali metal or alkaline earth metal carboxylate salt. 
     
     
       19. The method of claim  15  wherein the carboxylate salt is selected from the group consisting of sodium formate, sodium acetate, and sodium propionate. 
     
     
       20. The method of claim  15  wherein the aqueous composition is saturated with carboxylate salt. 
     
     
       21. The method of claim  15  wherein the aqueous composition has a density of about 8 ppg to about 19 ppg at 70° F. 
     
     
       22. The method of claim  15  wherein the aqueous composition has a density of about 8.4 ppg to about 9.8 ppg at 70° F. 
     
     
       23. The method of claim  15  wherein the metal surface comprises carbon steel. 
     
     
       24. The method of claim  15  wherein the aqueous composition further comprises a halide salt. 
     
     
       25. The method of claim  15  wherein hydrogen sulfide is present in the brine. 
     
     
       26. The method of claim  1  wherein the carboxylate salt comprises sodium bromide and sodium formate. 
     
     
       27. The method of claim  1  wherein the carboxylate salt comprises from about 16 to about 32 wt % sodium bromide and about 6 to about 14 wt % sodium formate. 
     
     
       28. The method of claim  1  wherein the aqueous composition has a density of between 8 and 19 ppg at 70° F. 
     
     
       29. A method to prevent corrosion on a metal well surface comprising contacting the metal surface with a composition comprising brine and a C1 to C4 carboxylate salt solution having a density of 8-19 ppg at 70° F. wherein the brine also contains carbon dioxide and/or hydrogen sulfide. 
     
     
       30. The method of claim  29  wherein brine/carboxylate salt composition further comprises a halide salt selected from the group consisting of alkali metal and alkaline earth metal halide salts. 
     
     
       31. The method of claim  30  wherein the halide salt is NaBr, NaCl, KCl, and or KBr, the carboxylate salt is a formate, an acetate, a propionate, a butyrate, and/or a 2-methyl propionate salt. 
     
     
       32. The method of claim  29  wherein the carboxylate salt is a lithium, potassium, sodium, rubidium or cesium salt. 
     
     
       33. The method of claim  29  wherein the brine/carboxylate salt composition is calcium free. 
     
     
       34. The method of claim  14  wherein the brine further comprises carbon dioxide dissolved or entrained therein. 
     
     
       35. The method of claim  14  wherein the brine further comprises hydrogen sulfide dissolved or entrained therein. 
     
     
       36. The method of claim  34  wherein the brine/carboxylate salt composition is calcium free. 
     
     
       37. The method of claim  14  wherein the halide salt is selected from the group consisting of alkali metal and alkaline earth metal halide salts. 
     
     
       38. The method of claim  14  wherein the halide salt is NaBr, NaCl, KCl and/or KBr. 
     
     
       39. The method of claim  14  wherein the carboxylate salt is a lithium, potassium, sodium, rubidium or cesium salt. 
     
     
       40. The method of claim  14  wherein the carboxylate salt is a formate, an acetate, a propionate, a butyrate, and/or a 2-methyl propionate salt.